Hydrofoil craft



N. W. GARDINER HYDROFOIL CRAFT July 15, 1952 6 Sheets-Sheet 1 Filed July 22, 1949 July 15, 1952 N. w. GARDINER HYDROFOIL CRAFT 6 Sheets-Sheet 2 Filed July 22, 1949 July 15, 1952 N. w, G DlNER 2,603,179

HYDROFOIL CRAFT Filed July 22, 1949 6 s g t '3 y 1952 N. w. GARDINER 2,603,179

HYDROFOIL CRAFT Filed July 22, 1949 6 Sheets-Shet &

N. w. GARDINER HYDROFOIL. CRAFT July 15, 1952 6 Sheets-Sheet 5 Filed July 22, 1949 QUE llxxl 111 July 15, 1952 N. w. GARDINER HYDROFOIL CRAFT 6 Sheets-Sheet 6 Filed July 22, 1949 Patented July 15, 1952 STATES HYDROFOIL CRAFT Neil William Gardiner, Great Auclum, Burghfield Common, England 18 Claims. (01. lid-66.5)

This invention relates to improvementsv in hydrofoil craft and in particular it relates to means for. automatically adjusting the angle of attack of the. hydrofoils in dependence on the state of the water surface ahead of the craft to cause the craft to ride over any Wave formation upon the water surface.

In United States patent specification .No. 955,343 hydrofoil craft are described in which the angle of attack of the hydrofoils is controlled by means of a control plate floating upon the water surface directly above thehydrofoils. This control plate is secured to an arm which is in turn pivotally mounted. to the craft and is connected through suitable linkages to the hydrofoils. The control plate follows the wave surface and varies the angle of attack of the hydrofoils with the object of maintaining the latter at a substantially constant depth of immersion. The disadvantage of acont-rol'plate of this nature is that it does not predict the wave surface until the waves have struck the'bow of the craft and have reached the control plate. The-craft will not therefore rise above the wave surface until the wave has travelled along a substantial length of the craft.

-In- United- States' patent specification No. 2,387,987 hydrofoil craft are described in which a control plane, comprising a float or skid floats upon or' kims along the water surface ahead of the craft. This control plane is again mounted on an arm pivotally secured to the craft and connected through suitable linkages. to the hydrofoils. This arrangement overcomes the main disadvantage of the control plate of U. S.

patent specificationNo. 955,343 in that the float or skidpredicts the wave surface ahead of the craft and varies the angle of attack of the hydrofoils in time for the craft to rise above the waves as it meets them. 7

It is well known that the leeward side of a wave crest tends to be steeper than the windward side. If the force of the wind is'sufiicient to cause the wave crests to break into white horses the water at these crests has assumed a sufficiently steep angle on the leeward side to become unstable. In a confused sea where waves d .riving from different origins meet, such as when a freshening wind blows at an angle to a swell, the points of juncture of the waves tend to become even steeper. "A control plane, comprising a float or skid, which is caused to float upon or alon" wave formations of the above mentioned natures tends to bounce on the steep wave crestsj This bounding of the control plane causes sudden variations in the angle of attack-of the 2 hydrofoils with the result that the craft does not ride steadily.

Sudden large increases in the angle of incidence of a main hydrofoil introduce a further disadvantage in that the negative pressure above the hydrofoil drops still further and encourages the formation of air bubbles upon its upper sur-.

face with consequent loss in the lift which the hydrofoil exerts upon the craft.

It is the object of the present invention to provide means for predicting the water surface ahead of hydrofoil craft which overcomes the above mentioned disadvantages.

According to the present invention themain hydrofoils of hydrofoil craft are each pivotally mounted on a strut rigidly secured to the forepart of the craft each hydrofoil being connected through a suitable linkage to a dihedral angled predictor hydrofoil travelling through the water ahead of the craft with the upper surface of said predictor hydrofoil at least partially submerged.

A fioat or skid travelling at speed across the water surface derives its lift entirely from the pressure of Water acting upon its under surface. Theupper surface of the float or skid can never contribute towards the lift. On the other hand a hydrofoil comprising a flat or cambered surface travelling through the water totally submerged derives approximately one third of its lift from the water pressure on its under surface and the other two thirds of its lift from the reduction in pressure upon its upper surface. It is well known that a totally submerged hydrofoil has considerably less drag than a floating object which is adapted to give the same degree of lift. If such a hydrofoil is secured to an arm pivotally mounted to the bow of a craft, and projecting forward from the craft it will take up a totally submerged position whilst the craft is at rest. If now the craft is set in forward motion the, lift on the hydrofoil will cause it to rise to the water surface where it will act as a float or. skid deriving its lift entirely from the water pressure upon its .lower surface. It will remain in this position until the speed of the craft is reduced to such an extent that the weight of the hydrofoil overcomes the upward lift when it will become totally submerged once more. A flat hydrofoil of this nature would suffer from the same disadvantages as the control planes of the hitherto known hydrofoil craft. If now the flat hydrofoil is replaced by a dihedral angled predictor hydrofoil according to the present invention' at least part of the upper surface of the hydrofoil will always be submerged and the lift on such a hydrofoil will be derived chiefly from the reduced pressure upon the submerged portion of its upper surface. When the craft is at rest the predictor hydrofoil will be totally submerged. As the craft gathers speed the upward lift on the hydrofoil will overcome its downward loading and it will rise towards the water surface. The predictor hydrofoil will then travel through the water partially submerged to such a depth that the lift on the hydrofoil arising from the immersion of its lower parts balances the downward loading. The higher surfaces of the dihedral angled hydrofoil will be raised above the water where they perform no useful work until they become submerged again due to a reduction in speed of the craft or by meeting a wave. Conversely when the hydrofoil passes the crest of a wave the area of the submerged surfaces is decreased and therefore the lift exerted by the hydrofoil decreases. The kinetic energy stored in the mass of the predictor hydrofoil is absorbed by the stream of water passing over the lowest point of the dihedral angle. This stream of water resists any tendency for the hydrofoil to bounce.

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a side elevation of the bow of a hydrofoil craft provided with predictor hydrofoils according to the invention,

Figure 2 is a partly sectioned side elevation on an enlarged scale showing the mounting of a predictor hydrofoil to a jockey arm,

Figure 3 is an elevation on the line IIIIII of Figure 2,

Figure 4 is a plan view corresponding to Figure 3,

Figure 5 is a front elevation of a predictor hydrofoil,

Figure 6 is a plan view corresponding to Figure 5,

Figure '7 is a section on the line a-a of Figure 2,

Figure 8 is a section on the line bb of Figure 2,

Figure 9 is a section on the line 0-0 of Figure 2,

Figure 10 is a side elevation, partly broken away, showing the connection of a jockey arm to the main hydrofoils of the craft,

Figure 11 is a section on the line XI-XI of Figure 1, with the jockey arms removed;

Figure 12 is a plan view corresponding to Figure Figure 13 is a side elevation similar to Figure 1, showing a modification of a detail, and

Figure 14 is a side elevation of an alternative connection of a jockey arm to the main hydrofoils of the craft.

Referring to Figures 1 to 12 the hydrofoil craft comprises a hull I which is adapted to float on the water when the craft is at rest, or travelling at low speed, the approximate water line under these conditions being indicated by the line DD (Figure 1). In the vicinity of the bow of the craft are two vertically depending struts 2 (Figure 1'1) one on each beam, rigidly secured to the hull I. Pivotally mounted to the lower extremity of each strut 2 is a main hydrofoil 3. The angle of attack of each of the main hydrofoils 3 is controlled by the movement in a substantially vertical plane of an incidence command rod 4 pivotally connected at its lower end to the hydrofoil 3 and passing vertically upwards therefrom. At its upper end the rod 4 is linked to the pre- 4 dictor mechanism which is more fully described hereinafter.

When travelling at high speed the hull of the craft rises from the water and is supported-in an elevated position by the main hydrofoils 3, the relative position of the water line under these conditions being indicated by the line E-E (Figure 1). The predictor mechanism now to be described causes the craft to lift over the waves as it meets them, by varying the angle of attack of the main hydrofoils 3, so that drag is not produced on the hull I by contact with the water.

A predictor mechanism is provided for each of the main hydrofoils 3, each such mechanism comprising a jockey arm 5 pivotally mounted adjacent the bow of the craft (in a manner to be more fully described hereinafter) and extending forward from the craft ahead of its associated main hydrofoil 3. At the forward end of each jockey arm 5 there is mounted a gimbal joint, generally designated 6, comprising a sleeveformed ring I which is pivotally secured to the jockey arm 5 by means of bolts 8 passing through the forked end 9 of the jockey arm and entering threaded holes III in the ring I. Passing through the ring I of the gimbal joint 6 in a substantially vertical plane is a predictor hydrofoil rod I I the lower end of which is rigidly secured to the boss I2 of a dihedral angled predictor hydrofoil generally designated I3. The predictor hydrofoil I3 comprises an inverted V-shaped member I4 of aerofoil section having a positive angle of attack mounted on a V-shaped member I5 also of aerofoil section and having a predominantly positive angle of attack. The member I5 preferably comprises an upper portion I6 having a small dihedral angle and a positive angle of attack and a lower portion I! having a larger dihedral angle and preferably having a slight negative angle of attack. A stabilising fin I8 may be secured to the underside of member I4 to ensure correct alignment of the predictor hydrofoil when it is travelling through the water at speed. The boss I 2 is mounted on the upper surface of member I4 adjacent its leading edge.

A sleeve I3 is fitted over the upper end of rod II in which sleeve the rod II is free to rotate, said sleeve being pivotally connected, by means of bolts 20 to the forked end 2| of a secondary arm 22 which at its other end is pivotally mounted at 23 (Figures 10 and 11) to the hull I.

Secured to the rear end of each jockey arm 5, by means of bolts 24 (Figure 10), is an apertured plate 25. The aperture in plate 25 receives an eccentric 25 mounted on a shaft 21 passing transversely across the craft (Figure 11). The rear end of each jockey arm is pivotally connected at 28 to the forked upper end 29 of the incidence command rod 4.

When a wave approaches the craft the dihedral angled predictor hydrofoil I3 will rise relative to the craft due to the increased lift on the hydrofoil arising from the immersion of its upper surfaces by the wave. The jockey arm 5 pivots on the eccentric 26 and depresses the incidence command rod 4 so depressing the trailing edge of the main hydrofoil 3 causing the latter to assume an increased angle of attack. The craft then rises over the wave predicted by hydrofoil I3. When the wave passes the predictor hydrofoil the latter falls relative to the craft to restore the angle of attack of the hydrofoil 3 to the value existing before the approach of the wave.

The slight negative angle of attack of the lower portion I! of the predictor hydrofoil ensures that '5 the latter falls without leaving the waterwhen the upper parts of portion -I 6 break surface.

The length ofrthe secondary arm 22 may be such that the pivotal mounting 23, eccentric 26 and bolts 8 and 2!) lie at the four corners of a parallelogram in which case, as the predictor hydrofoil rises and falls with the water surface ahead of the craft, the angleof attack of the predictor hydrofoil remains substantially constant. Alternatively the length of secondary arm 22 may be adjusted so that the angle of attack of the predictor hydrofoil varies as the jockey arm swings through its arc of travel. To this end thesecondary arm 22 may be provided with oppositely threaded end portions 30, 3! entering the ends of the central portion 32. Rotation of the central portion in one direction or the other will then increase or decrease the length of the secondary arm 22. Locknuts 33, 34 may be provided to clamp the threaded portions 30, 3| to the central portion 32 when the secondary arm has been adjusted to the desired length. Alternatively the locknuts 33, 34 may be omitted a worm wheel 35 then being mounted .on the central portion 32 which can be rotated from within the craft by means of a worm 36 and handle 3'! (Figure The level at which the craft travels above the water surface may be adjusted by means of the eccentric 26. eccentric 26 to raise or lower the trailing edge of the hydrofoil 3 independently of the position of the predictor hydrofoil l3. The position of eccentric 26 will be adjusted so that the height of the craft above the water surface is suitable for the wave surface being encountered. Shaft 21 may be rotated from within the craft by any suitable means, for example by means of a worm and worm-wheel generally designated 41 (Figure .11).

When the craft is travelling at low speed with its hull in the water, or when the craft is stationary, the predictor hydrofoil l3 will be totally submerged and will be positioned below the level of the hydrofoils 3. If the craft isto'be beached the delicate predictor hydrofoil will therefore be the first part of the craft to-touch bottom. In order to prevent the predictor hydrofoil from being damaged in this manner. a stop- 33 may be secured to-the hull which limits the downward arc of travel of the jockey arms '5. Alternatively a float 39 (Figure 13) may be secured to the ring 1, the said float being so positioned and of such dimensions that when it floats on the water surface it supports the predictor hydrofoil 13 above the level of the main hydrofoils .3. When the craft increases speed, but before it commences to rise from the water surface, the predictor hydrofoil is lifted to its normal operating position and the float is lifted clear of the water surface where it can exert no influence on the control of the angle of attacker the main hydrofoils 3.

To facilitate a quick lift of thejOckey arms 5 as the craft gathers speed from rest one or more flat hydrofoils 55 (Figures 1 and 12) may be provided above the predictor hydrofoil i3. fiat hydrofoils may be mounted on the ring 7 in which case they may have either a constant or variable angle of attack according to the setting of the secondary rod 22. Alternatively they maybe mounted on the jockey arm itselfat such an angle that they present a positive angle of attack when the predictor hydrofoil is inits lowest position when the craft is starting from rest. .As thespeed of the craft increases and Rotation of shaft 21 causes the These- "6 the predictor hydrofoil rises to its operating position, the flat hydrofoils 40 are lifted clear of the water.

Generally speaking the maximum angle of at-' tack which it is desirable that the main hydro foils .3 shall assume is in the region of +8 degrees. Top-revent the hydrofoils exceeding this angle of attack when the jockey arms 5 are at'the upper limit of their are of travel the linkage illustrated in Figure 14 may be employed. Referring to this figure the incidence command rod 4 is provided at its upper end with a plate 4| having an arcuate slot 42 therein. 7 A peg 43 secured to the rear extremity of the jockey arm 5 engages within the slot 42. A stop 44 mounted on the command rod 4 is positioned so that it engages a stop 45 secured to the strut-2 when the main hydrofoil has attained its maximum desirable angle of attack. Any further movement of the jockey arm 5 in a direction tending to increase the angle of attack of the main hydrofoil, after the stop M has engaged the stop 45,

will merely result-in the peg 43 moving along the slot 42. The reaction of the water on the main hydrofoils when the craft is travelling at speed ensures that thepegs 43 will alwaysengage with the upper extremity of slot 42 when the stop 44 is not engaging stop 45.- Ifdesired however a spring loaded arm 45 may be pivotally mounted on the eccentric 25 having its free end bearing on the upper end of plate 41. Thisspring loaded arm ensures that the incidence command rod 4 follows the movements of the jockey arm faithfully when the latter is subjected to rapid changes in position.

Although a particular form of dihedralangled hydrofoil it has been described above which has a diamond shaped profile when viewed from the front and which has a chord length decreasing towards its lowest point, it is to be understood that the inventionisLnot limited to'this particular form of hydrofoil. For example the dihedral angled predictor hydrofoil may consist of a V-shaped member, similar to member 15, or a- V-sha-ped member having a constant dihedral angle. Whatever the form of the dihedral angled predictor hydrofoil it -is always arranged to have a predominantly positive angle of attack, both in its nor-maloperating position and when 'in its lowermost totally submerged position. As previously mentioned the lowest part of the dihedral angle predictor hydrofoil may have a small negative angle of attack working against the larger surfaces above it which have a positive angle, to ensure that the predictor take up its own alignment. "If the -rod 'H is not allowed freedom of rotation it is found that the predictor hydrofoil I 3 has a tendency to steer the-craft. v

The depth at which the predictor hydrofoil t3 runs when the craft is travelling at h-igh speed is dependent on the weight of the predictor as sembly balancing the mmand lift thereon. If his found that the depth at which theupper surface of the predictor hydrofoil runs isinsufiicient and that there is a tendency'for the said hydrofoil to break surface the assembly may be provided with means, preferably some 'form fo'f spring loading, urging the predictor hydrofoil downwards to increase its loading. The degree of this loading may be adjustable from within the craft so that the depth of immersion of the predictor hydrofoil can be set to suit the prevailing water surface conditions.

Although I have described a preferred method of mounting the predictor hydrofoil to its jockey arm it is to be understood that the invention is not limited to this particular arrangement. Any other form of support for the predictor hydrofoils may be used which allows them to travel through the Water surface following the wave contours at a fixed or variable angle of attack and which allows them freedom to take up their own alignment.

In the above description given with reference to the accompanying drawings the jockey arm is connected directly to the main hydrofoil incidence command rod. The invention is again not limited to this particular arrangement for the movement of the jockey arm may be caused to operate the main hydrofoils of the craft through hydraulic, pneumatic, electrical or kinetic energy actuators of the type described in United States Patent No. 2,576,716, dated November 27, 1951.

I have found that in practice a dihedral angled predictor hydrofoil according to the present invention travels through the wave surface ahead of the craft responding very accurately to the wave crests without any degree of bounce. In fact it is found that the predictor hydrofoil responds to waves which are of insufficient height to strike the hull of the craft when travelling on its main hydrofoils. In order to prevent unnecessary correction of the angle of attack of the main hydrofoils when the predictor hydrofoil is subjected to very quick short movements a cushioning device may be interposed between the jockey arm and the main hydrofoil incidence command rod or between the jockey arm and the main hydrofoil actuating mechanism. Thus the jockey arm shaft 2! may be mounted on bearings which are allowed slight vertical movement against hydraulic or pneumatic pressure means. Alternatively the jockey arm may be connected to the incidence command rod or hydrofoil actuating mechanism through a cylinder and piston in which the working fluid may be air or liquid. The cylinders may be provided with an adjustable valve, the setting of which can be adjusted from within the craft so that the degree of variation of the angle of attack of the main hydr'ofoils in response to movement of the predictor hydrofoils can be adjusted to suit the prevailing water surface condition.

What I claim is:

1. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; means connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack which is connected to the front end of said jockey arm, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of. said main hydrofoil with its upper surface partially submerged when the craft travels .wit its hull above the water surface.

2. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; a substantially vertically disposed incidence command rod connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to 'said strut; a gimbal joint comprising a sleeve formed ring pivotally mounted intermediate its ends to the front end of said jockey arm; a substantially vertically disposed rod passing through and rotatably mounted within said ring; a secondary arm comprising front and rear ends; the front end of said secondary arm being pivotally connected to the upper end of said rotatably mounted rod and the rear end of said secondary arm being pivotally secured to the forepart of the hull; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack rigidly secured to the lower end of said rotatably mounted rod, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when the craft travels with its hull above the water surface.

3. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a shaft secured to the forepart of the hull and passing transversely across the craft; a jockey arm comprising a front end projecting forwardly of the hull and a rear end; means intermediate the ends of said jockey arm mounting the jockey'arm for pivotal movement about said shaft; means connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a gimbal joint comprising a sleeve-formed ring pivotally mounted intermediate its ends to the front end of said jockey arm; a substantially vertically disposed rod passing through and rotatably mounted within said ring; a secondary arm comprising front and rear ends, the front end of said secondary arm being pivotally connected to the upper end of said rotatably mounted rod and the rear end of said secondary arm being pivotally secured to the forepart of the hull; means for adjusting the length of said secondary arm; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack connected to the lower end of said rotatably mounted rod, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when the craft travels with its hull above the water surface.

4. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end 'of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end;

. means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; means mounted on the hull to limit the downward pivotal movement of the front end of said jockey arm; a substantially vertically disposed incidence command rod connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack connected to thefront end of said jockey arm, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when the craft travels with its hull above the water surface.

5. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the .hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; means connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a gimbal joint comprising a sleeve-formed ring pivotally mounted intermediate its ends to the front end of said jockey arm; a substantially vertically disposed rod passing through and rotatably mounted within said ring; float means secured to said gimbal joint to limit the downward pivotal movement of said front end of' said jockey arm when the craft is at rest; a secondary arm comprising front and rear ends, the front end of said secondary arm being pivotally connected to the upper end of said rotatably mounted rod and the rear end of said secondary arm being pivotally secured to the forepart of the hull; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack rigidly secured to the lower end of said rotatably monuted rod, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when the craft travels with its hull above the water surface.

6. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a rotatable shaft mounted in the forepart of the hull and passing transversely across the craft; an eccentric secured to said shaft; a jockey arm comprising a front end projecting'forwardly of the hull and a rear end; an apertured plate mounted on said jockey arm intermediate the ends thereof receiving said eccentric in the aperture therein and mounting said jockey arm' for pivotal movement about said eccentric; a substantially vertically disposed incidenc command rod connecting the rear end of said jockey arm to said main hydrofoil at a point lying to the rear of the pivotal mounting of said main hydrofoil to said strut; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack connected to the front end of said jockey arm, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when the craft travels with its hull'above the water surface.

7. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a rotatable shaft mounted in the forepart of the hull and passing transversely across the craft; an eccentric secured to said shaft; a jockey arm comprisinga front end projecting forwardly of the'hull and a rear end; an apertured plate mounted on said jockey arm in termediate the ends thereof receiving said eccentric in the aperture therein and mounting said jockey arm for pivotal movement about theeccentric; means connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a gimbal joint comprising a sleeve-formed ring pivotally mounted intermediate its ends to the front end of said jockey arm; a substantially vertically disposed rod passing through and rotatably mounted within said sleeve-formed ring; a secondary arm comprising front and rear ends, the front end of said secondary arm being pivotally connected to the upper end of said rotatably mounted rod and the rear end of said secondary arm being pivotally secured to the forepart of the hull; means for adjusting the length of said secondary arm; and a dihedral angled predictor hydrofoil comprising an inverted V-shaped member having a positive angle of attack secured to the lower end of said rotatably mounted rod and a lower V-shaped member having a predominantly positive angle of attack secured to and depending from said inverted V-shaped member, the dihedral angle of said predictor hydrofoil causing it to travel through the-water ahead of said mainhydrofoil with the lower V-shaped member at least partially submerged when the craft travels with its hull above the water surface.

8. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; a substantially vertically disposed incidence command rod pivotally connected at its lower end to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a plate mounted on the upper end of said incidence command rod; a substantially verticalarcuate slot formed in said plate; a peg secured to the rear end of said jockey arm received by said arcuate slot; stop means on said incidence command roll adapted to engage furtherstop means mounted .on said strut to limit the maximum angle of attack which said main hydrofoil can assume; and a dihedral angled predictor hydrofoil comprising a V-shaped member of aerofoil section having a predominantly positive angle of attack connected to the front endv of said jockey arm, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with said V-shaped member partially submerged when the'craft travels with its hull above the water surface. 1

9; Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; a substantially vertically disposed incidence command rod pivotally connected at its lower end to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a plate mounted on the upper end of said incidence command rod; a substantially vertical arcuate slot formed in said plate; a peg secured to the rear end of said jockey arm received by said arcuate slot; stop means secured to said incidence command rod adapted to engage further stop means mounted on said strut to limit the maximum angle of attack which said main hydrofoil can assume; a gimbal joint comprising a sleeve-formed ring pivotally mounted intermediate its ends to the front end Of said jockey arm; a substantially vertically disposed supporting rod passing through and rotatably mounted within said ring; float means secured to said gimbal joint to limit the downward pivotal movement of the front end of said jockey arm when the craft is at rest; a secondary arm comprising front and rear ends; the front end of said secondary arm being pivotally connected to the upper end of said supporting rod and the rear end of said secondary arm being pivotally secured to the forepart of the hull; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack rigidly secured to the lower end of said supporting rod; the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when the craft travels with its hull above the water surface.

10. Hydrofoil craft comprising a hull; a stru rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a rotatably mounted shaft in the forepart of the hull and passing transversely across the craft; an eccentric secured to said shaft; a jockey arm comprising a front end projecting forwardly of the hull and a rear end; an apertured plate mounted on said jockey arm intermediate the ends thereof receiving said eccentric in the aperture therein and mounting said jockey arm for pivotal movement about said eccentric; a substantially vertically disposed incidence command rod pivotally connected at its lower end to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a plate mounted on the upper end of said incidence command rod; a substantially vertical arcuate slot formed in said plate; a peg secured to the rear end of said jockey arm received by said arcuate slot; an arm comprising front and rear ends pivotally mounted at its front end in said aperture in said apertured plate; a spring housed in said strut bearing at one end on said arm at a point intermediate the ends of the latter to urge the rear end of said arm into engagement with the upper extremity of said plate mounted at the upper end of the incidence command rod; and a dihedral angled predictor hydrofoil comprising an inverted V-shaped member having'a positive angle of attack secured to the front end of said jockey arm and a lower V-shaped member having a predominantly positive angle of attack secured to and depending from said inverted V-shaped member, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of the main hydrofoil with the lower V- shaped member partially submerged when the craft travels with its hull above the water surface.

l1. Hydrofoil craft comprising a hull; a-strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; means connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; and a dihedral angled predictor hydrofoil comprising an upper inverted V -shaped member having a positive angle of attack secured to the front end of said jockey arm, a lower V-shaped member having a predominantly positive angle of attack secured to and depending from the upper inverted V-shaped member, said lower V- shaped member comprising an upper portion having a small dihedral angle and a lower portion having a larger dihedral angle, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of the main hydrofoil with said lower V-shaped member partially submerged when the craft travels with its hull above the water surface.

12. Hydrofoil craft according to claim 11 in which the upper portion of said lower V-shaped member has a positive angle of attack and the lower portion of said lower V-shaped member has a slight negative angle of attack.

13. Hydrofoil craft according to claim 12 in which the chord length of said lower V-shaped member decreases towards the lowest point of the member.

14. Hydrofoil craft as claimed in claim 13 comprising a stabilizing fin secured to said upper inverted V-shaped member.

15. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotallymounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; means connecting the rear end of said jockey arm to said main hydrofoil at a point lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a flat hydrofoil having a positive angle of attack mounted on said jockey arm ahead of the pivotal mounting of said jockey arm to the hull; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack connected to the front end of said jockey arm, the dihedral angle of said predictor hydrofoil'causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when surface.

16. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a rotatably mounted shaft in the forepart of the hull and passing transversely across the craft; an eccentric secured to said shaft; a jockey arm comprising a front end projecting forwardly of the hull and a rear end; an apertured plate mounted on said jockey arm intermediate the ends thereof receiving said eccentric in the aperture therein and mounting said jockey arm for pivotal movement about said eccentric; a substantially vertically disposed incidence command rod pivotally connected at its lower end to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a plate mounted on the upper end of said incidence command rod; a substantially vertical arcuate slot formed in said plate; a peg secured to the rear end of said jockey arm received by said arcuate slot; stop means on said incidence command rod adapted to engage further stop means mounted on said strut to limit the maximum angle of attack which the main hydrofoil can assume; a gimbal-joint comprising a sleeve-formed ring pivotally mounted intermediate its ends to the front end of said jockey arm; a substantially vertically disposed supporting rod passing through and rotatably mounted within said sleeve-formed ring; float means secured to said gimbal joint to limit the downward pivotal movement of the front end of said jockey arm when the craft is at rest; a secondary arm comprising front and rear ends, the front end of said secondary arm being pivotally connected to the upper end of said supporting rod and the rear end of said secondary arm being pivotally secured to the forepart of the hull; means for adjusting the length of said secondary arm; and a dihedral angled predictor hydrofoil comprising an upper inverted V-shaped member having a positive angle of attack secured to the lower end of said supporting rod, a lower V- shaped member secured to and depending from said upper inverted V-shaped member, said lower V-shaped member comprising an upper portion of aerofoil section having a small dihedral angle and a positive angle of attack and a lower portion of aerofoil section having a larger dihedral angle and a slightly negative angle of attack, the chord length of said lower v-shaped member decreasing towards the lowest point of the member, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with the lower portion of said lower V-shaped member at least partially submerged when the craft travels with its hull above the water surface.

17. Hydrofoil craft comprising a hull; two struts rigidly secured to the forepart of the hull, one on each beam of the craft and depending downwardly from the hull; means mounting a main hydrofoil for pivotal movement at the lower end of each of said struts; two jockey arms each having a front end projecting forwardly of the hull and a rear end; a shaft secured to the forepart of the hull and passing transversely across the craft; means intermediate the ends of each jockey arm mounting said jockey arms one at each end of said shaft for pivotal movement about said shaft; means connecting the rear end of each of the jockey arms to one of the main hydrofoils at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to its strut; and two dihedral angled predictor hydrofoils each comprising upper and lower surfaces and each having a predominantly positive angle of attack, one predictor hydrofoil being connected to the front end of each of said jockey arms, the dihedral angle of said predictor hydrofoils causing themto travel through the water ahead of the main hydrofoils with their upper surfaces partially submerged when the craft travels with its hull above the water surface.

18. Hydrofoil craft comprising a hull; a strut rigidly secured to the forepart of the hull and depending downwardly therefrom; a main hydrofoil pivotally mounted at the lower end of said strut; a jockey arm having a front end projecting forwardly of the hull and a rear end; means secured to the forepart of the hull mounting said jockey arm for pivotal movement about a point intermediate its ends; a substantially vertically disposed incidence command rod connecting the rear end of said jockey arm to said main hydrofoil at a point on the latter lying to the rear of the pivotal mounting of said main hydrofoil to said strut; a gimbal joint comprising a sleeveformed ring pivotally mounted intermediate its ends to the front end of said jockey arm; a substantially vertically disposed rod passing through and rotatably mounted within said ring; a secondary arm comprising front andrear ends, the front end of said secondary arm being pivotally connected to the upper end of said rotatably mounted rod and the rear end of said secondary arm being pivotally secured to the forepart of the hull; and a dihedral angled predictor hydrofoil comprising upper and lower surfaces and having a predominantly positive angle of attack rigidly secured to the lower end of said rotatably mounted rod, the dihedral angle of said predictor hydrofoil causing it to travel through the water ahead of said main hydrofoil with its upper surface partially submerged when the craft travels with its hull above the water surface, and the rigid connection between said predictor hydrofoil and said rotatably mounted rod enabling said predictor hydrofoil to turn freely about the axis of said rotatably mounted rod, thereby preventing said predictor hydrofoil from steering the craft.

NEIL WILLIAM GARDINER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

